This invention relates to hydrocarbon oils and more particularly to hydrocarbon oils having improved pour points.
In the storage, transportation and use of hydrocarbon fuel oils, e.g. crude oils, gas oils, distillate fuel oils, such as heating oils, diesel oils, turbo-jet fuels and residual fuel oils and the like, problems associated with the pour point of the oils have been long recognized. The pour point of an oil is defined as the lowest temperature at which the oil will flow when chilled without disturbance under specified conditions. Pour point problems arise through the formation of solid or semi-solid waxy particles in the oils when the oils are subjected to low temperatures in storage. A related problem also exists in respect of hydrocarbon residual fuel oils and waxy crude oils, in which the waxy components adversely affect the flowability and/or pumpability of the oil under low temperature conditions.
The formation of solid or semi-solid waxy particles in fuel oils and in waxy crude oils at temperatures just below their pour point causes serious distribution and/or operating difficulties. For example, the distribution of fuel oil by pumping is rendered difficult or impossible at temperatures below the pour point of the oil. Likewise, the flow of the oil at such temperatures through filters in heating systems cannot be maintained, resulting in the failure of the equipment to function. The formation of solid or semi-solid waxy particles in wax-containing crude oils gives rise to difficulties in the movement of such crude oils through pipelines at low ambient temperatures.
With respect to fuel oils, the aforementioned problems have been in part, remedied by lowering the end points of oils used for blending heating and diesel oils. It has also been suggested that the fuel oils, particularly distillate fuel oils, may be dewaxed, as for example, by urea dewaxing. However, dewaxing operations are costly and readjustment of end points causes a loss of valuable product as blending material for fuel oil stocks.
Another approach in overcoming the problem has been to attempt to find a pour point depressant which will lower the pour point of the fuel oil or crude oil. This is sometimes done to lower the pour point of lubricating oils. However, materials which are effective in lowering the pour point of lubricating oils are usually ineffective as pour point depressants for fuel oils or crude oils.